• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.05a
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• pp.76-79
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• 1996

Polypyrrole films were electrochemically synthesized under a constant current condition ranging from 50 ${\mu}$A/$\textrm{cm}^2$ to 2 mA/$\textrm{cm}^2$ with resultant high electrical conductivity about 100 S/cm. Specific energy of 70 Wh/kg and Ah efficiency of 97% were achieved during the cycling using liquid electrolyte system. On the other hand, consequences of the cycling were 51 Wh/kg and 95% using PEO$\sub$8/LiClO$_4$PC$\sub$5/EC$\sub$5/ solid electrolyte system. Polypyrrole film can be cycled stable and Ah efficiency is excellent, so it can be applicable to the cathode of Lithium secondary batteries.

• Korean Journal of Organic Agriculture
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• v.9 no.4
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• pp.53-69
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• 2001

The word \"permaculture\" is a contraction of \"permanent agriculture\" or \"permanent culture\". Permaculture principles are designed to support (or ensure) the survival of humanity, the earth and all on it, and, to improve our standard of living, Permaculture can be defined as : a design system for creating sustainable human environments that can be (relatively) easily constructed and maintained. The principles of permaculture designs are relative location every element (such as house , rice paddy, road, esc) is placed in relation to each other such that each assists the other : each element performs multiple functions ; each function is supported by many elements : energy efficient planning ; using biological resources rather than fossil fuels : energy cycling on site (both fuel and human energy) : Using and accelerating natural plant succession to establish favourable sites and soils ; poly-culture and diversity of beneficial species for a productive, interactive system ; use of edge and natural patterns for best effect. These principles can be used for any permaculture design, in any climate, and at any scale. There has been very little scientific examination of Permaculture, and as such, it must be viewed as a design philosophy.viewed as a design philosophy.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1954-1957
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• 2005

A quantitative evaluation of postural balance training using a virtual reality bicycle system was performed. In the experiment, the effectiveness of virtual reality bicycle system on postural balance training was analyzed with four male subjects in their twenties. The parameters measured during cycling were cycling time, average velocity, number of times subject deviated from path, and weight shift. Those parameters were evaluated for the quantification of the extent of control. We also measured the parameters on postural control capability after 5th trial and 10th trial in a balance testing system with a force plate to find out the effectiveness of the training. In the balance test with force plate, it was found out that the weight shift was almost zero and the deviation from the target trace reduced significantly after the training with the virtual cycle. The result showed that the virtual bicycle system was an effective system as a rehabilitation training device.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.6
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• pp.3037-3054
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• 2019

Public bicycle system (PBS) is a new emerging and popular mode of public transportation. PBS data can be adopted to analyze human movement patterns. Previous work usually focused on specific scales, and the relationships between different levels of hierarchies are ignored. In this paper, we introduce a multi-scale and interactive visual analytics system to investigate human cycling movement and PBS usage condition. The system supports level-of-detail explorative analysis of spatio-temporal characteristics in PBS. Visual views are designed from global, regional and microcosmic scales. For the regional scale, a bicycle network is constructed to model PBS data, and an flow-based community detection algorithm is applied on the bicycle network to determine station clusters. In contrast to the previous used Louvain algorithm, our method avoids producing super-communities and generates better results. We provide two cases to demonstrate how our system can help analysts explore the overall cycling condition in the city and spatio-temporal aggregation of stations.

• Journal of Korea Foundry Society
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• v.24 no.4
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• pp.194-201
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• 2004

• Journal of Biomedical Engineering Research
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• v.23 no.3
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• pp.207-216
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• 2002

This Paper describes a quantitative analysis of Postural balance training using virtual bicycle system. We have used a virtual bicycle system that combines virtual reality technology with a bicycle . In this experiment, 20 normal adults were tested to investigate the influencing factors on Postural balance. Several factors including cycling time. cycling velocity. number of times of Path deviation, center of Pressure(COP) . and weight shift were extracted and evaluated to quantify the extent of control. Also, To improve the effect of balance training, we investigated the usefulness of visual feedback information by weight shift The results showed that the system was effective Postural balance rehabilitation training device and. in addition. the analysis method might have a wider applicability to the rehabilitation field.

• Journal of Digital Convergence
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• v.11 no.11
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• pp.313-320
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• 2013

The four-dimensional cycle simulator, which can recognize whether the road is ascent or descent, its gradient, and status of its surface on Virtual Reality, is introduced in this paper. On the base of these recognitions, various virtual motion path situations are displayed on LCD monitor attached ahead. These various situations may support not only the sense of realty but also an interest in a game in opposition to previous exercise cycles that might be monotonous. In this paper both analysis and estimation of basic bodily abilities for the four-dimensional cycling are addressed.

• Journal of Communications and Networks
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• v.18 no.2
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• pp.201-209
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• 2016

In wireless sensor networks (WSNs) duty cycling has been an imperative choice to reduce idle listening but it introduces sleep delay. Thus, the conventional WSN medium access control protocols are bound by the energy-latency tradeoff. To break through the tradeoff, we propose a radio wave sensor called radio frequency (RF) wakeup sensor that is dedicated to sense the presence of a RF signal. The distinctive feature of our design is that the RF wakeup sensor can provide the same sensitivity but with two orders of magnitude less energy than the underlying RF module. With RF wakeup sensor a sensor node no longer requires duty cycling. Instead, it can maintain a sleep state until its RF wakeup sensor detects a communication signal. According to our analysis, the response time of the RF wakeup sensor is much shorter than the minimum transmission time of a typical communication module. Therefore, we apply duty cycling to the RF wakeup sensor to further reduce the energy consumption without performance degradation. We evaluate the circuital characteristics of our RF wakeup sensor design by using Advanced Design System 2009 simulator. The results show that RF wakeup sensor allows a sensor node to completely turn off their communication module by performing the around-the-clock carrier sensing while it consumes only 0.07% energy of an idle communication module.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.1363-1364
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• 2007

The composites such as Sn-CNTs, $SnSb_{0.5}$-CNTs and $CoSb_3$-CNTs have attracted much attention in the past years owing to their good overall properties. In these samples, intermetallic compounds show high specific capacities. Recently, interest in metal oxides such as $Al_{2}O_{3}$, MgO and $TiO_2$ has been largely stimulated by the realization that they can improve the cycling stability of the Li-ion battery electrodes. The reversible capacity of the $TiO_2$/CNTs composite reaches 168 mAh $g^{-1}$ at the first cycle and remains almost constant during long-term cycling. In this study, a nanocomposite of $TiO_2$/CNTs was prepared by sol-gel method and its electrochemical properties as anode materials for Li-ion batteries were studied by galvanostatic cycling, cyclic voltammograms (CV) and electrochemical impedance spectroscopy (EIS).

• Transactions of the Korean Society of Mechanical Engineers A
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• v.40 no.3
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• pp.259-265
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• 2016

Recently, life prediction models for Pb-based and Pb-free solders used in chip resistor assemblies under thermal cycling have been introduced. The models suggest that the field lifetimes of Pb-free solders would be better than those of Pb-based solders when used for chip resistors under thermal cycling conditions, while the lifetime of the chip assemblies under accelerated test conditions show a reverse relationship. In this study, the prediction models were verified by applying the model to another research case. Finite element models were built, thermal cycling conditions were applied, and the energy densities were calculated. Finally, life prediction analysis was conducted for the cases where Pb-based and Pb-free solders were used. The prediction results were then compared with the test data of the case. It was verified that the predictions of the developed life cycle models are on the practical scale.